Automatic thermostatic circuit breaker and maker



AUTOMATIC THERMOSTATIC CIRCUIT BREAKER AND MAKER Original Filed Oct. 30, 1931 2 Sheets-Sheefl I Wm 7 w m mi llllllllllll 1 35 IHHIHHI 6 Fig.6

F. D. SHELDON Sept. 3, 1935.

AUTOMATIC THERMOSTATIC CIRCUIT BREAKER AND MAKER Original Filed Oct. 30, 1931 2 Sheets-Sheet 2 Fla. /4

I 1 UQJ 2 F0 Patented Sept. 3, 1935 UNITED STATES AUTOMATIC THERMOSTATIC CIRCUIT BREAKER AND MAKER Frank D. Sheldon, Chicago, Ill., assignor to Olive Pement Sheldon, Chicago, Ill.

Application October 30, 1931, Serial No. 572,067 Renewed January 24, 1935 8 Claims.

The object of this invention is to provide a device that will automatically break a circuit should an abnormal current occur and will after a predetermined lapse of time, which will usu- 5 ally allow sufficient time for the removal of the cause for such a condition, automatically close the circuit. A fusible member forms a part of the circuit of this automatic circuit breaker and maker and should the breaker fail to operate this fusible member will blow and break the circuit the same as in any standard type of plug. A further object of this invention is to minimize the are established upon breaking of the circuit by having in shunt a resistance with the stationary contact which resistance the current must pass through upon opening of the main contact points thereby reducing the flow of current and the established arc is reduced in proportion,the opening and closing motions of 0 contacts are of a rapid nature which also tends to reduce the size of are that is established.

A novel feature of this invention is the inclusion within the limited confines of a standard fuse plug, a substantial circuit breaker and maker with a time delay closing device and a fusible member capable of handling the current which these fuse plugs are designed to carry. Another novel feature of this invention is the arrangement of the various parts in separate chambers in order to thoroughly insulate and protect its various units. Thermal actuating unit is novel, wherein the various sections of bimetallic flexible grid the current passes back and forth providing the necessary resistance for its operation-each section of the grid adding to the torque to operate contact levera fusible strip may constitute one section of grid-all within the confines of its location in assembly. The contact lever is novel inasmuch as the rotative motion of the o actuating trunnion imparts first a sliding motion towards axis of trunnionthereby shearing any minor points of fusion of contacts, then a rotary motion separating the contacts. A further novel feature is the delayed time closing device which will keep contacts apart a predetermined lapse of time and contact lever then will close with a rapid motion. This device is adjustable.

These objects and the several features of this invention will be best understoodfrom a consideration of the following description taken in connection with the accompanying drawings which form a part of this specification, with the further understanding that while the drawings show a. practical form of the invention, the latter is not confined to any strict conformity with the showing of the drawings, but may be changed and modified so long as such changes and modiflcations make no material departure from the salient features of this invention.

The invention consists in the novel parts and arrangement of parts to be described hereinafter, all of which contribute to produce an eflicient automatic thermostatic circuit breaker and maker.

A preferred embodiment of the invention is described in the following specification while the broad scope of the invention is pointed out in the appended claims.

In the drawings Fig. 1 is an elevation of an automatic thermostatic circuit breaker and maker embodying my invention;

Fig. 2 is a composite vertical section of an automatic thermostatic circuit breaker and maker so arranged as to show clearly the arrangement of its various parts;

Fig. 3 is a plan view of circuit breaker and maker with protecting cover removed with contacts closed showing arrangement of fusible member, contacts with one type of contact lever shown and delayed time closing device;

Fig. 4 is a plan view showing fuse window in cover plate;

Fig. 5 is a horizontal section through base showing assembly of thermostatic actuating unit. fuse chamber and contact chamber;

Fig. 6 is a perspective view of thermostatic actuating unit assembled with its trunnions and supporting members before being formed into its helical form. Upper trunnion as shown is for operation in combination as shown in Fig. 3;

Fig. 7 shows the design of upper trunnion of actuating unit for use with contact lever as shown in plan view of Fig.

Fig. 8 is a perspective showing a detail of the central terminal or abutment of the circuit breaker and maker which engages the central contact of the socket which this invention is screwed into, and the lower trunnion of the actuating unit is in flexible contact with.

Fig. 9 is a perspective of contact lever as shown in Fig. 3.

Fig. 10 is a perspective of connecting link part of time delay closing device shown in Fig. 3.

Fig. 11 is a plan view with cover plate removed showing arrangement of fusible member, contacts with a second design of contact lever and time delay closing device;

Fig. 12 is an elevation of circuit breaker and maker showing arrangement of shunt resistance in broken away section; v

Fig. 13 is a wiring diagram showing path of current through circuit breaker and maker without are reducing resistance; and

Fig. 14 is a wiring diagram showing path of current through circuit breaker and maker with arc reducing resistance.

In the drawings I indicates the body, or body portion, of circuit breaker and maker, of a molded insulation provided with ventilating holes 2-3 the lower part is shaped to receive a threaded metal terminal 4 which adapts circuit breaker and maker to be screwed into an ordinary screw type of lamp socket. This body to house resistance element 5 is formed with a channel-like depression 6 on outer periphery of upper part of body I and cover cap I when in position form a chamber giving full mechanical and electrical protection to resistance 5. Body I ha three chambers, 33 for the actuating unit shown in Fig. 6, 9 for contacts I2 and I3 and contact arm I4 or I5, and time delay closing device as shown in Figs. 3 and l1, II] for the fusible member and when a resistance element is used an additional chamber 6. Chambers 9 and III are covered by cover plate 24 with fuse window 25 and is held in position in body I by groove 26, or cover cap I with fuse window. Closing of actuating unit chamber 33 is effected by a base cover plate 21 of suitable insulating material, and is provided with ventilating holes 28--base cover plate 21 also supports contact 29 which has flexible contact with lower trunnion 3| of actuating unit shown in Fig. 6base cover plate held in position with body I by the inwardly projecting ledge 41 of terminal 4, and suitable means provided between parts I and 2'! to hold part 21 from rotation relative to part I.

The thermostatic actuating unit Fig. 6, and shown in assembly Figs. 2 and 5 is composed of a number of sections of flexible bimetal forming a grid 34, a stationary grid holding member 35 of a suitable insulating material with lower and upper trunnions 36 and 31 a part of same and a rotatable holding member 38 which supports grid 34 and trunnions 3| and 32 or 3| and 39 as shown in Figs. 6 and 7. The lower trunnion 3| is in metallic contact with metal terminal 29. The upper trunnion 32 or 39 has metallic contact with upper part of grid 34 and passes loosely through partition separating chambers 33 and 9 and contact lever I5 is fixedly attached to upper end of trunnion 39. This grid construction of thermoflexible element 34 provides several torque units in one piece, permitting the construction of a strong actuating unit suitable for the purpose of this invention. Trunnion projections 36 and 31 of part 35 fit into recesses 41 of body I and 30 of base cover plate 21 allowing free movement for the various positions part 35 may take at any time. The bearing 48 of part 32 or 39 fits into opening 49 provided in partition between chambers 9 and 33. Trunnion 3| is preferably split by groove 40 to permit a close contact with part 29. Trunnion 32 with pin 42 fits into hole 43 of contact lever I4-which hole is of such design that during the first part of rotative movement of trunnion 32, the lever I4 moves toward the trunnion axis shearing any minor fusions of contacts I2 and I3 and further rotative movement of trunnion 32 causes lever I4 carrying contact I3 to rotate, separating contacts I2 and I3 thereby breaking the circuit.

Mechanism for time delay closing device and quick closing of contacts is shown in two forms, one in Fig. 3 and the other in Fig. 11. Construction shown in Fig. 3 comprises a link II with hole 44 and pin I8 fitting in depression of pressure spring I9. Spring pressure is obtained by means of screw 5| and pressure plate 20. The fulcrum of spring is at 53. It will be observed from drawings Fig. 3 that pins I8 and 45 are on one side of center of trimnion axis, allowing spring I9 to help keep contacts I2 and .I3 engaged. A slight rotative movement of contact lever I4 causes pin 45 to be in a straight line with pin I8 and center of trunnion 32. Further rotative movement of lever is assisted by spring l9 which accelerates movement of contact I3. The grid being of flexible bimetallic material is heated by the passage of an electric current and distorts from its normal position. An abnormal current rapidly heats grid causing rapid distortion of grid and being flexibly attached at one side and the other side free to follow a rotary path on account of being held by holder 38 causing part 38 to rotate on trunnions 3| and 32 or 3| and 39. This opening phase cycle is performed in a short interval of time whereas the reverse or closing cycle takes a much longer period of time. In this closing cycle the grid returns to its original position by giving up the heat units imparted to it by the passing of electric current and this cooling is accomplished by the equalizing of the temperatures of the heated grid and the cooler air in chamber 33. While the cooling of grid is progressing the returning cycle of grid 34 to its normal position is opposed by the spring I9 until suflicient energy is stored up in grid 34 to pass pin 45 over the point that is in a straight line with center of trunnion 32 and pin I8. Then spring I9 assists the closing movement of lever I4, thus closing the circuit in a rapid manner. In Fig. 11 the time delay closing device is sim pler, consisting of a lever 2| fastened to trunnion 39 having a pin 22 in contact with spring 23 whose tension is adjusted by screw 5|. In the breaking of circuit, pin 22 rests on flat part of spring 23 when contacts are engaged and practically offers no resistance to rotative movement of lever 2| but as soon as pin 22 reaches incline I lever 2| is assisted in the opening cycle of contact lever I5. In the closing cycle as the cooling of grid progresses it is constantly opposed by pin 22 climbing incline I of spring 23 until the torque developed by the cooling grid 34 is greater than that exerted by spring 23. After pin 22 reaches high'point of incline I, lever 2| with contact lever I5 moves rapidly causing a rapid closing of contacts. It is now disclosed that both opening and closing cycles are accomplished with rapid motions and that part of the closing cycle is retarded by the device just described. Contact I3 is fastened to contact lever I4 or l5 and contact I2 with its support is supported by body I and is connected to terminal 4 and when fusible member II is in circuit contact I2"is connected to it and fusible member II in its own chamber III is in turn connected to terminal 4 through lead 54. Under certain conditions it is necessary that finely divided particles of an insulation may 1111 chamber I3 and also that chamber Ill be subdivided by partitions into two or more compartments.

When conditions warrant the introduction of an are reducing device the circuit is altered as shown in Fig. 14 to include a resistance element 5 in shunt with contacts I2 and I3 through which the current must pass immediately upon breaking of contact engagement thereby reducing the flow of current to desired limits and practically only a small arc occurs upon contact I3 disengaging with contact 3 and contact l2.

It is evident that I have provided an automatic thermostatic circuit breaker and maker with a delayed time closing device and a fusible member in circuit that will automatically break a circuit when an overload occurs and will, after a predetermined lapse of time, automatically close the circuit. This device is interchangeable with the standard type of fuse plugs now in general use.

I claim:

1. An automatic circuit-interrupter comprising a hollow body of insulating material, a shaft having a center part of insulation and metal shaft ends journaled in the body, a bi-metal element of generally rectangular form secured at one end to said insulation and anchored at the other within the body, said element being notched part way from the shaft end to cause current to traverse its length, said element being connected at its two ends to the metal shaft ends, a fixed switch contact, a movable contact carried by said shaft and movable therewith, whereby current of more than a predetermined current strength passing through the shaft and element causes the shaft to be rotated to open the movable switch contact. I

2. An automatic circuit-interrupter comprising a hollow body of insulating material, a shaft having a center part of insulation and metal shaft ends journaled in the body, a bi-metal element of generally rectangular form secured at one end to said insulation and anchored at the other within the body, said element being notched part way from the shaft end to cause current to traverse its length, said element being connected at its two ends to the metal shaft ends, a fixed switch contact, a movable contact carried by said shaft and movable therewith, whereby current of more than a predetermined current strength passing through the shaft and element causes the shaft to be rotated to open the movable switch contact, said element on cooling restoring the contact to closed position.

3. An automatic circuit-interrupter comprising a hollow body of insulating material, a shaft having a center part of insulation and metal shaft ends iournaled in the body, a bi-metal element of generally rectangular form secured at one end to said insulation and anchored at the other within the body, said element being notched part way from the shaft end to cause current to traverse its length,- said element being connected at its two ends to the metal shaft ends, a fixed switch contact, a movable contact carried by said shaft and movable therewith, whereby current of more than a predetermined current strength passing through the shaft and element causes the shaft to be rotated to open the movable switch contact, said element on cooling restoring the contact to closed position, and means for delaying the closing of the contact.

4. An automatic circuit-interrupter comprising a hollowbody of insulating material, a shaft having a center part of insulation and metal shaft ends iournaled in the body, a bi-metal element or" generally rectangular form secured at one end to said insulation and anchored at the other within the body, said element being notched part way from the shaft end to cause current to traverse its length, said element being connected at its two ends to the metal shaft ends, a fixed switch contact, a movable contact carried by said shaft and movable therewith, whereby current of more than a predetermined current strength passing through the shaft and element causes the shaft to be rotated to open the movable switch contact, said element on cooling restoring the contact to closed position, and spring-actuated means for delaying the closing of the contact.

5. An automatic circuit-interrupter comprising a hollow body of insulating material, a shaft having a center part of insulation and metal shaft ends journaled in the body, a bi-metal element of generally rectangular form secured at one end to said insulation and anchored at the other within the body, said element being notched part way from the shaft end to cause current to traverse its length, said element being connected at its two ends to the metal shaft ends, a fixed switch contact, a movable contact carried by said shaft and movable therewith, whereb'y current of more than a predetermined current strength passing through the shaft and element causes the shaft to be rotated to open the movable switch contact, said element on cooling restoring the contact to closed position, and spring-actuated means which at first delays the closing the contact up to a certain point and then acceler ates its closing.

6. An automatic circuit-interrupter adapted to have a current flowing therethrough comprising a hollow body enclosing two switch contacts, one of which is movable, a thermal element through which current passes operable by changes in temperature due to changes in the strength of current flowing therethrough to cause said movable contact to open the switch when the strength of current exceeds a predetermined amount, and means tending to further open the switch after it has opened a predetermined amount, said means also tending to retard closing of the switch, said body having a chamber enclosing the thermal element and a chamber enclosing the switch contacts and said means.

'7. An automatic circuit-interrupter comprising a hollow body ofinsulating material, a shaft having a center part of insulation and metal shaft ends journaled in the body, a bi-metal element of generally rectangular form secured at one end to said insulation and anchored at the other within the body, said element being slotted longitudinally to cause current to traverse substantially the entire area of the element, a fixed switch contact, a movable contact carried by said shaft and movable therewith, whereby current of more than a predetermined current strength passing through the shaft and element causes the shaft to be rotated to open the movable switch contact.

8. An automatic circuit-interrupter comprising a hollow body of insulating material, a shaft having a center part of insulation and metal shaft ends journaled in the borhr, a bi-metal element of generally rectangular form secured at one end to said insulation and anchored at the other within the body, said element being slotted longitudinally to cause current to traverse substantially the entire area of the element, a fixed switch contact, a movable contact carried by said shaft and movable therewith, whereby current of more than a predetermined current strength passing through the shaft and element causes the shaft to be rotated to open the movable switch contact, the bi-metal element acting to close the contact as said element cools off.

FRANK D. SHELDON. 

